MythBusters Episode 60: "Earthquake Machine"
Air Date: August 30, 2006
Nikola Tesla invented a machine that when attached to an object and tuned to vibrate at a certain frequency, can cause an earthquake-like effect on the object it is attached to.
busted
The MythBusters built several variations of Tesla’s pneumatic "earthquake machine" using modified jackhammers, as well as a specially designed computer-controlled electromagnetic linear actuator made by Grant. Small scale tests on metal bars were mixed, with the modified tools performing poorly while the more finely-tunable actuator produced significant vibrations in the bar. A scale test with a model of Tesla’s lab and miniature motor failed to produce any noticeable result. Finally, a large scale test using an actual bridge was attempted. The MythBusters attached the resonator to the side of a large truss bridge to see whether the entire bridge would be shaken. While the resonator did match the bridge’s frequency and produce a vibration noticeable 100 ft away, it was not strong enough to be considered an earthquake. With the combination of the lack of spectacular results and Tesla’s tendency to exaggerate his accomplishments at the time of publication, the MythBusters declared the myth busted.
Placing a lava lamp on a stove will cause an explosion that could kill a person.
confirmed
All lava lamp tests produced violent reactions. The reactions differed depending on the lamp’s design. When lava lamps with safety caps exploded, they vented their contents out through the top of the lamp because of the safety cap popping off (as designed). A bottlecapped lava lamp being tested leaked due to a poor seal, and was helped to explode with a spray of cold water (through the thermal stress caused by the cooling effect of the water on the glass). The explosion lodged a piece of glass deep into a ballistics gel dummy planted near the lamp. A jumbo lava lamp exploded with enough force to pierce the dummy with numerous shards of glass. With the combination of the violent explosion, glass shrapnel in the dummy, explicit warning labels, and a recorded incident, the myth was deemed confirmed.
Placing a can of beans on a stove will cause an explosion that could kill a person.
confirmed
The cans of beans tested exploded with force proportional to the size of the can. Larger cans explode more violently than smaller cans, especially since large cans do not have a weakened pop-open top, but the build team concluded that any can of beans on a stove is potentially lethal.
Placing a can of potted meat on a stove will cause an explosion that could kill a person.
busted
Though the can of potted meat exploded rather violently, the explosion did not have enough force to be deemed lethal.
Placing a large glass jug of milk on a stove will cause an explosion that could kill a person.
plausible
The jar of milk exploded violently, though not with a large amount of force. The build team concluded that an exploding jar of milk can be lethal if a person happened to be standing over it.
Just a query. Could not the stroke be adjusted as the frequency is maintained in the Tesla Earthquake machine? Would this not then be like the person pushing somebody on the swing? Would not it cause an increase in the swaying?
June 26, 2007 at 10:40 AMThe final (25 Hz) frequency that was arrived at was one of the secondary frequencies, not the primary frequency required. Keep dividing that frequency by 2 be patient tweek it a little and the bridge WILL come down!!! Tesla was a genius!
July 7, 2007 at 10:25 PMSome engineers use a machine that vibrates to test buildings designs against earthquakes. They should research actual information before resorting to their parlor tricks. The busters attempts are busted.
July 8, 2007 at 10:05 AMDo these machines actually destroy the buildings they are used on?
July 18, 2007 at 10:52 PMParticularly given that their “experiment” went to a bridge (and an old bridge at that, built before “Galloping Girdy” and the lessons learned there), I was surprised that the Mythbusters a) didn’t mention the Tacoma-Narrows bridge collapse which was presumably caused by nothing more than the wind setting up the correct resonance frequency and b) that given that bridge collapse took 4 months, they so quickly presumed that there was no chance that the “earthquake machine” would have collapsed the bridge after just one hour.
September 12, 2007 at 8:52 PMWhat was the computer-controlled electromagnetic linear actuator used in this episode? I need to make a shaker chair to oscillate in 3 axis and i think 3 actuators will work well?
September 12, 2007 at 11:21 PMAlso trying to figure-out what the make/model was of Grant’s Linear Servo Actuator … for a School Science Project :-)
September 13, 2007 at 12:04 PMHello everyone. I was thinking about the tesla machine. They didn’t do much research like usual. I’ve been working in the cnc/machining for a very long time and I can say when the high speed machining hits that special spot with a well worn out cnc machine (1-2 tonne) they can go out of control. Crack cement moving up to a couple of feet. So the idea is not that fart fetch. They just didn’t make there research properly. I’ve seen a old lathe jump a whole feet up in the air lol with the same princaple.
December 9, 2007 at 11:17 PMI remember a strange bottle of Coke I got from the store. It was a glass quart bottle but inside was the socket from a wrench, a bolt, and other assorted hardware. It was a curiosity I kept on my dresser. One time I showed it to a friend, set it back down on the dresser, and soon after we walked out of the room it exploded. My bedroom was covered with sharp glass shrapnel and the walls, floor, and ceiling were soaked in sticky Coke. I figure the Coke was reacting with the metal, creating a gas buildup and when I jostled it the reaction sped up to explosive pressure.
January 15, 2008 at 9:00 PMI do like the lava lamp experiment but was the lamp in the myth an original lamp or a modern retro remake. The original lamps were made from a screw top bottles were the new ones have the bottle top cap ?
March 13, 2008 at 2:44 PMThis is in regard to Grant’s actuator mounted to the bridge. Though wind moves across bridges, it is the vortices of the wind moving over and through the bridge structure that generates rolling and/or vertical oscillations. Bridges are less likely to oscillate side to side. Unfortunately, Adam and Jamie mounted Grant’s actuator horizontally on a diagonal truss beam, many feet above the roadbed. Despite what I consider a poor choice of mounting direction and location, they seemed to be mildly impressed with their results. I would love to see Tesla vindicated in a do-over of this experiment: only this time mount the actuator vertically on a vertical structure at the center of the bridge span. I would also suggest starting the test without adding six pounds to the actuator. They may attain an impressive enough result without it.
May 29, 2008 at 1:13 AMThe frequency is different for every structure, it has to be tuned.
June 4, 2008 at 7:33 PMThe man was a genius. Who worked a life time on his work and in a hour episode can call it busted.
July 26, 2008 at 6:32 PMyes i concure a redo of the tesla myth is requisite. too much psuedo science in that episode for it to be a reliable test.
October 5, 2008 at 8:54 PMYES PLEASE DO MORE TESLA STUFF! Unless of course you are forbidden by government pressures you can’t talk about.
October 17, 2008 at 9:01 PMThis needs to be redone to the present-day mythbusters standards of excellence. Make the earthquake machine large enough to take the bridge down.
November 1, 2008 at 10:58 AMI thought Tesla tested his earthquake machine on a building. Not some bridge designed to withstand the vibrations and resonances caused by lifetime of heavy traffic. Is that building where they dropped the elevator still standing? Or maybe something bigger!
November 19, 2008 at 1:41 AM